# 读MMA7660三轴加速度传感器数据
# 2021/7/31/1/20
import machine
import struct
import time

class MMA7660:
    sclpin=machine.Pin(11)
    sdapin=machine.Pin(10)
    
    def init(self):
        global i2c
        i2c=machine.SoftI2C(scl=MMA7660.sclpin,sda=MMA7660.sdapin,freq=400000)
        print('MMA7660 address={}'.format(i2c.scan()[0]))
        # 使能
        i2c.writeto_mem(76,7,b'1')
        time.sleep_ms(10)
        print('MMA7660 init')
        
        
    def close(self):
        i2c.writeto_mem(76,7,b'0')
        print('MMA7660 closed')
        
        
    def _bit2num(self,x):
        xsign=(x&32)>>5  # 取符号位
        x=x&31     # 取数值
        if xsign==1:
            x=-x
        return x
        

    def readxyz(self):
        x=i2c.readfrom_mem(76,0,8)
        y=i2c.readfrom_mem(76,1,8)
        z=i2c.readfrom_mem(76,2,8)
        
        # 数据转换
        # 6bit结果输出,移位操作
        x=struct.unpack('<B',x)[0]
        y=struct.unpack('<B',y)[0]
        z=struct.unpack('<B',z)[0]
        
        # 调用函数，6位转为数字
        x=MMA7660.bit2num(self,x)
        y=MMA7660.bit2num(self,y)
        z=MMA7660.bit2num(self,z)

        return x,y,z

    def readtilt(self):
        
        tilt_data=i2c.readfrom_mem(76,3,8)
        tilt_data=struct.unpack('<B',tilt_data)
        tilt_data=int(tilt_data[0])
        
        # Bafro 00 unknown 01 Front 10 Back
        Bafro=(tilt_data<<6)>>6

        # PoLa 000 unkonwn 001 Left 010 Right 101 Down 110 Up
        PoLa=(tilt_data&28)>>2
        pos=0
        if PoLa==0:
            pos='unknown!'
        elif PoLa==1:
            pos='Left'
        elif PoLa==2:
            pos='Rignt'
        elif PoLa==5:
            pos='Down'
        elif PoLa==6:
            pos='Up'
        return pos